Scissor stack assemblies, more commonly known as scissor lifts, are well known and used in many fields. A scissor lift is a type of platform which can usually only move vertically. Public institutions, ports, bridge maintenance, electrical companies, warehouses, arbor care, and construction are just a few of the industries that utilize scissor lifts. The lifts provide temporary access for people or equipment to inaccessible areas, usually at a height. The mechanism to achieve this is the use of linked, folding supports or arms in a criss-cross ‘X’ pattern, known as a pantograph. The upward motion is achieved by the application of pressure to the outside of the lowest set of supports, elongating the crossing pattern, and propelling the work platform vertically. The platform may also have an extending ‘bridge’ to allow closer access to the work area (because of the inherent limits of vertical only movement).
The contraction of the scissor action can be hydraulic, pneumatic or mechanical (via a leadscrew or rack and pinion system). Depending on the power system employed on the lift, it may require no power to enter ‘descent’ mode, but rather a simple release of hydraulic or pneumatic pressure. This is the main reason that these methods of powering the lifts are preferred, as it allows a fail-safe option of returning the platform to the ground by release of a manual valve.
The lifts generally include outer and inner supports that form the pantographs. Generally, the outer and inner support members are made of rectangular shaped steel tubes, and include a number of apertures or through holes through both walls of the tubes. Bosses are typically inserted through adjacent holes of the outer and inner members, and pins are inserted through them. Constructing the scissor lifts in this manner involves a large amount of time, as well as a large amount of materials. It can be time and material consuming to insert a boss and pin through each set of holes of aligning inner and outer support members of the pantographs. After the bosses and pins have been inserted, a manufacturer must ensure that all of the pins inserted through the members have been retained by bolts or other retaining and/or securing means, which further increases the time and amount of materials required. Additionally, connecting the members with bosses and pins retained at both the outer and inner members decreases the rigidity of the members as both the outer and inner members include bearing joints, which increase movement (known as “play”) between the members, decreasing the structural strength of the lifts. The play, or movement, is caused by the number of moving parts of the assembly. Most lifts include tubes with at least three holes for inserting bosses and members. Therefore, each tube will have at least three locations with parts moving in relation to one another.
Another issue with inserting pins through multiple holes in each of the inner and outer members involves treating the pins to avoid corrosion. When the pins are inserted through the members, their ends and possibly a portion of the pin bodies are exposed. As the pins are often made from steel, or a steel bar, the exposed portions and ends may rust or corrode in normal elements. Therefore, the ends and exposed portions must be plated or treated in some manner. To ensure the utmost safety in constructing the scissor lift, it is vital that any and all portions or the steel pins be treated to prevent corrosion. The treatment of all of the pins is time and labor consuming, and requires checking at regular intervals to insure that no portion of the pins has started corroding, which could potentially reduce the structural integrity of the scissor lift.
Once the pantographs have been assembled, it is common that a manufacturer or user may need to route cables, wires, and/or hoses from the bottom of the lift to the top. The routing may be accomplished in many ways. One is to route or direct the hose, cable, and/or wire back and forth inside the tubes, looping on each end between the tubes. This method does not result in a very clean look, as portions of the hose, cable, and/or wire remain outside the tubes. A cleaner way to route the cables, hoses, and/or wires from the bottom of the scissor lift to the top is to cap the tube ends and route along the inside of the tubes. This method can become expensive because it takes some apparatus, such as a tray system, to jump from section to section, and there may be a lot of jumps to make depending on the height of the scissor lift.
Therefore, there is a need in the art to provide a scissor stack assembly that can be manufactured using fewer parts to increase the rigidity of the assembly. There is also a need in the art to provide an assembly that provides for fewer moving components during use of the assembly. Additionally, there is a need in the art for an improved method of routing a hose, cable, and/or wire from the bottom portion of a lift assembly to an upper portion of a lift assembly that is clean looking, inexpensive, and efficient.
It is therefore a primary object, feature, and/or advantage of the present invention to overcome or improve on the deficiencies in the art.
It is another object, feature, and/or advantage of the present invention to provide an improved scissor stack assembly that includes fewer moving parts during operation to increase the rigidity of the assembly.
It is another object, feature, and/or advantage of the present invention to provide an improved scissor stack assembly that reduces the number of parts required to assemble the scissor stack.
It is another object, feature, and/or advantage of the present invention to provide an improved scissor stack assembly that includes the use of a preplated steel bar to make pins that are corrosion-resistant.
It is another object, feature, and/or advantage of the present invention to provide an improved scissor stack assembly that covers non-plated ends of pins to prevent corrosion of the non-plated portions or ends of the pins.
It is another object, feature, and/or advantage of the present invention to provide an improved scissor stack assembly that retains outer support members to inner support members only by a cap covering a pin extending from the outer member through the inner member.
It is another object, feature, and/or advantage of the present invention to provide an improved scissor stack assembly that includes welding pins to outer members to extend from the outer members through the inner members.
It is yet another object, feature, and/or advantage of the present invention to provide a method of routing a cable, hose, and/or wire from the bottom or lower portion of a scissor stack assembly to an upper location of the scissor stack assembly.
It is still another object, feature, and/or advantage of the present invention to provide a method of routing a cable, hose, and/or wire from a lower portion to an upper portion of a scissor stack assembly using wire forms and tie cables positioned alongside the tubes of the assembly.
These and/or other objects, features, and advantages of the present invention will be apparent to those skilled in the art. The present invention is not to be limited to or by these objects, features and advantages. No single embodiment need provide each and every object, feature, or advantage.